基坑开挖前降水引起的地面沉降的工程实例分析  

Case study on settlement around an unexcavated foundation pit due to groundwater pumping

作　　者：孙文娟[1] 沈水龙[1] 李耀良[2] 唐翠萍[1] 

机构地区：[1]上海交通大学船建学院土木工程系,上海200030 [2]上海市基础工程公司,上海200001

出　　处：《岩土工程学报》2008年第S1期314-318,共5页Chinese Journal of Geotechnical Engineering

基　　金：上海市重点学科建设项目(B208)

摘　　要：上海浦东新区某基坑工程开挖前抽水260d,观测到的基坑内的沉降为0.20～0.30m不等。为分析基坑地下水位变化、土体渗流场的变化以及坑内外地面沉降,对基坑建立了三维有限元分析模型。分析结果与现场实测资料基本吻合,表明所用方法可以较好的模拟实际工程。在进一步的计算分析中分别考虑了含水层和隔水层对地面沉降值的影响,结果表明在抽取承压含水层水时,初期是由于承压含水层释水压密引起,但是沉降量较小,随着时间的增长,黏土层固结产生沉降,而这部分沉降量较大,为基坑抽水引起的主要沉降。During the dry excavation of deep foundation pit,groundwater must be pumped in or around the pit,and the seepage of groundwater forms a groundwater level depression cone around the pit.The drawdown of the groundwater level will cause the increase of effective stress of soft soil.Thus,the soft clay will consolidate and settlement will occur in or around the pit.A case history on the settlement in and around an unexcavated pit due to groundwater pumping was presented.Before excavation the groundwater was pumped for 260 days,and about 0.20~0.30 m-settlement in the pit was observed.Settlement was also observed around the pit.In order to analyze the variation of groundwater level,seepage in the subsoil,and ground surface settlement,a 3D finite element model was adopted.The analytical results indicate that by using the geotechnical parameters the proposed method can simulate the field measured values well.Further analysis shows that the settlement is mainly induced by the compression of aquitard I.

关 键 词：基坑开挖前 地下水抽取 三维有限元分析 地面沉降 

分 类 号：TU463[建筑科学—结构工程] P642.26[建筑科学—土工工程]